WSL9x: Add A Linux Subsystem To Your Windows 9x

April 23, 2026 by Maya Posch 19 Comments

Considering that Windows NT has the concept of so-called ‘subsystems’ whereby you can run different systems side-by-side, starting with the POSIX subsystem and later the Windows Subsystem for Linux (WSL), it was probably only a matter of time before someone figured that doing this with Windows 9x was also completely reasonable. Ergo we now got [Hailey Somerville]’s Linux Subsystem for Windows.

To make running Linux inside Windows 9x work, it was necessary to heavily patch a Linux kernel, as normally there are no provisions for such a subsystems in Windows 9x’s kernel unlike the NT kernel. Correspondingly, the Linux kernel is based on user-mode Linux and hacked to call Windows 9x kernel APIs instead of the POSIX ones.

In order to use WSL9x you thus need to build said modified Linux kernel – currently at version 6.19 – along with a disk image containing an installed copy of Windows 9x. From there WSL9x can be loaded with the wsl command and you’re then free to cooperatively run the Win9x and Linux kernel side-by-side. This is reminiscent of Cooperative Linux (coLinux), which did something similar except with Windows NT and Linux kernels running side-by-side, and of course we have WSL2 with Windows 10+.

Thanks to [adistuder] for the tip.

Trying To Build Your Own Consumer-Grade Router In 2026

April 16, 2026 by Maya Posch 47 Comments

Although we have many types of networking equipment with many unique names, at their core they can usually be reduced to just a computer with some specific peripherals. This is especially the case for something like a router, a device found in just about any home these days. Certain consumer-grade routers may contain something special like a VDSL modem, but most of them just have a WAN Ethernet jack on one end and one or more LAN-facing Ethernet ports.

All further functionality is implemented in software, including any firewall, routing and DHCP features. What this means is that any old PC with at least two Ethernet ports or equivalent can be a router as long as you install the appropriate software.

In this article we’ll be taking a look at what consumer-level options there exist here today, ideally something so simple that the average home user could set it up with a bit of coaching.

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Authenticate SSH With Your TPM

April 11, 2026 by Al Williams 20 Comments

You probably don’t think about it much, but your PC probably has a TPM or Trusted Platform Module. Windows 11 requires one, and most often, it stores keys to validate your boot process. Most people use it for that, and nothing else. However, it is, in reality, a perfectly good hardware token. It can store secret data in a way that is very difficult to hack. Even you can’t export your own secrets from the TPM. [Remy] shows us how to store your SSH keys right on your TPM device.

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USB, Abstracted

April 9, 2026 by Al Williams 16 Comments

Modern technology builds on abstractions. Most application programmers today don’t know what a non-maskable interrupt is, nor should they have to. Even fewer understand register coloring or reservation stations for instruction scheduling, and fewer still can explain the physics behind the transistors in the CPU. Sometimes tech starts out where you need to know everything (programming a bare-metal microprocessor, for example) and then evolves to abstraction. That’s where [WerWolv] wants to get you for writing USB code using the recent post USB for Software Developers.

Many USB tutorials assume you want to know about the intricacies of protocol negotiation, information about the hardware layer, and that you are willing to write a Linux kernel module to provide a driver. But thanks to abstraction, none of this has been absolutely necessary for many use cases for a long time.

While the post focuses on Linux, there is libusb for Windows. We presume the same principles would apply, more or less.

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Intel 486 Support Likely To Be Removed In Linux 7.1

April 7, 2026 by Maya Posch 46 Comments

Although everyone’s favorite Linux overlord [Linus Torvalds] has been musing on dropping Intel 486 support for a while now, it would seem that this time now has finally come. In a Linux patch submitted by [Ingo Molnar] the first concrete step is taken by removing support for i486 in the build system. With this patch now accepted into the ‘tip’ branch, this means that no i486-compatible image can be built any more as it works its way into the release branches, starting with kernel 7.1.

No mainstream Linux distribution currently supports the 486 CPU, so the impact should be minimal, and there has been plenty of warning. We covered the topic back in 2022 when [Linus] first floated the idea, as well as in 2025 when more mutterings from the side of [Linus] were heard, but no exact date was offered until now.

It remains to be seen whether 2026 is really the year when Linux says farewell to the Intel 486 after doing so for the Intel 386 back in 2012. We cannot really imagine that there’s a lot of interest in running modern Linux kernels on CPUs that are probably older than the average Hackaday reader, but we could be mistaken.

Meanwhile, we got people modding Windows XP to be able to run on the Intel 486, opening the prospect that modern Windows might make it onto these systems instead of Linux in the ultimate twist of irony.

A hex dump of the first iteration of the small ELF file

How Small Can A Linux Executable Be?

March 31, 2026 by Julian Scheffers 39 Comments

With ever increasing sizes of various programs (video games being notorious for this), the question of size optimization comes up more and more often. [Nathan Otterness] shows us how it’s done by minifying a Linux “Hello, World!” program to the extreme.

A naive attempt at a minimal hello world in C might land you somewhere about 12-15Kb, but [Nathan] can do much better. He starts by writing everything in assembly, using Linux system calls. This initial version without optimization is 383 bytes. The first major thing to go is the section headers; they are not needed to actually run the program. Now he’s down to 173 bytes. And this is without any shenanigans!

A hexdump of the final ELF file, significantly smaller than the original — The final tiny ELF file

The first shenanigans are extreme code size optimizations: by selecting instructions carefully (and in a way a C compiler never would), he shaves another 16 bytes off. But the real shenanigans begin when he starts looking for spaces in the ELF header that he can clobber while the program is still accepted by Linux: now he can move his already tiny x86_64 code into these “vacant” spaces in the ELF and program headers for a final tiny ELF file weighing in at just 120 bytes.

P.S.: We know it is possible to make this smaller, but leave this as an exercise to the viewer.

Using FireWire On A Raspberry Pi Before Linux Drops Support

March 27, 2026 by Maya Posch 31 Comments

Once the premium option for data transfers and remote control for high-end audiovisual and other devices, FireWire (IEEE 1394) has been dying a slow death ever since Apple and Sony switched over to USB. Recently Apple correspondingly dropped support for it in MacOS 26, and Linux will follow in 2029. The bright side of this when you’re someone like [Jeff Geerling] is that this means three more years of Linux support for one’s FireWire gear, including on the Raspberry Pi with prosumer gear from 1999.

If you’re not concerned about running the latest and greatest – and supported – software, then using an old or modern Mac or PC is of course an option, but with Linux support still available [Jeff] really wanted to get it working on Linux. Particularly on a Raspberry Pi in order to stay on brand.

Adding a FireWire port to a Raspberry Pi SBC is easy enough with an RPi 5 board as you can put a Mini PCIe HAT on it into which you slot a mini PCIe to Firewire adapter. At this point lspci shows the new device, but to use it you need to recompile the Linux kernel with Firewire support. On the Raspberry Pi you then also need to enable it in the device tree overlay, as shown in the article.

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